There are hard disk drives (HDDs) that store control firmware in a magnetic disk. For example, Japanese Patent No. 3415990 discloses a conventional HDD storage device that has firmware (a first part) on a flash read only memory (ROM). Activating the driving mechanism, the firmware loads data from a spare area of a disk medium into a static random access memory (SRAM). The conventional HDD storage device also has firmware (a second part) that is stored in the spare area of the disk medium and loaded into the SRAM therefrom or that is swapped into or out of the SRAM.
In such an HDD storage device, control firmware used for ordinary operation is stored in the magnetic disk, and is read from the magnetic disk using loader (initial firmware) stored in a nonvolatile memory. After that, firmware to be executed needs to be switched from the initial firmware to the read control firmware. Through conventional technologies, the firmware switch is performed while a magnetic head is once retracted to the ramp, or the firmware is changed (or added) not entirely but partly.
To accelerate the control, it is desirable that the firmware to be executed be switched from the initial firmware to the control firmware while the magnetic head extended to read the control firmware used for ordinary operation is kept above the magnetic disk. However, it is difficult for the conventional HDD storage device to perform such firmware switch. This is because servo control, interrupt control, and the like are generally required while the magnetic head is extended to above the magnetic disk, and part of the firmware always runs for the control operations (running firmware cannot be switched).